Variable speed drive



Aug. 3, 1937. R. cRzELLlTzER 2,088,948

l VARIABLE SPEED DRIVE Filed March '7. 1936 4 Sheets-Sheet 1 Aug, 3,1937. R. cRzELLlTzER VARIABLE SPEED DRIVE F11-ed March 7, 1956 4sheets-sheet 2 if @p ub@ m Aug. 3, 1937. R. cRzELLJTzER VARIABLE SPEEDDRIVE 4 sheets-sheet 3 Filed March '7, 1956 Vlas' radially with respectto said part.

Patented. Aug. 3, 1937 vian-.livr ENT o1=1=i^ci-iY VARIABLE srriip DRIVERobert Crzellitzer, Ivrea, Italy, assigner to Link- Belt Company,Chicago, Ill., a corporation of Illinois Application March 7, 1936,Serial No. IiM"IV, Ii1l'LA 416 Claims. (Cl. 82Z1) This inventionvrelatesjtira-variableilspeedr.con- '.trol device andr'hasf'or oneobject to provide 'a mechanism vfor"use-in:connectionwlthil-lathe/s-.and

otherfmachines for shaping, cutting, ilnishlng, `and otherwisetreating-pieces .of work in which aiconstant or approximately constantcutting speed is provided and is automatically maintained throughoutVthe cutting orv shaping operation.`

.Another object is to provide a Vconstant speed for an object or pointwhich moves in a generally `spiral path and `in connection with whichthe actual `rotational speed must be varied automatically to maintainconstant the speed of the point or object moving along such spiral path.

One application of the invention is in connection with turning andboring" lathes, facing lathesor trimming machines to maintain a constantcutting speed, irrespective ofl changes in the radius. Forthis purposethe rotational s peed of the member carrying the work must be varied inproportion to the variations in the radial position of thecuttingtoolwith respect to the work, and it is, therefore, one object ofthe invention to provide. a mechanism for automatically accomplishingsuch. variation.

Other objects will' appear from time to time in the specification and`claims.

The'invention is illustrated more or less diy agrammatically in`theaccompanying drawings, wherein: p

Figure l is a perspective, diagrammatic view illustrating one form ofthe invention;

Figure 2 is a perspective, diagrammatic view .illustrating a formsomewhat similar to that of Figure 1; l

Figure 3ds a disassembledl view in perspective, 4of the electricservomotor embodied in the de- `vice of Figure 2;

Figure 4 is a perspective, diagrammatic view illustrating a furthermodified form in which a ratchet mechanism is embodied;

Figure 5 is a perspective, diagrammatic View illustrating a stillfurther modified yform somewhatlsimilar to that of'` Figure 4,in whichthe ratchet mechanism is retained and in which an electric rheostat isalso used.

Like parts aredesignated by'like characters throughout Athespecification anddrawings.

In the several figures the invention is shown as applied to a lathe. IIt might,V of course, be applied to any similar. or analogous -machineor movement in connection with which it4 is desirable to maintain aconstant speed relation between a rotating part` and avmember which ismoved I indicates a support `and guide for an intermediate tool carrieror slide 2. 3 is thetool carrier proper, mounted .for transversemovement with respect to the intermediate carrier2 and itcarrles anysuitable tool l. The details of the lathe andthe tool carrying assemblyform no essential part of the present' invention and it is suiilcientfor'the purposes of this invention that some tool carrier be arrangedwhich is` movable and whose movement is controlled by the mechanismdescribed below in accordancel with the purposes of the invention.

5 is a threaded screw ori-spindle which engages a correspondinglythreaded portion 6 of the intermediate tool carrier 2 in such mannerthat upon rotation of the screw 5 the tool carrier is' moved, itsdirection of movement depending upon the direction of rotation of the'screw 5. By means of a driving connection comprising bevel or'othersuitable gears 1 the cross feed screw 5 is connected in the form shownin Figures 1 and 2, to a shaft 8 which carries a worm 9 and is .drivenby any suitable means aswll be described in detail below. In the formsshown in Figures 4 and 5 the cross feed screw 5 is connected by thegearing `I to a crank shaft I0. In all of the forms of the inventionshown, the movement of the shafts 8f and I0 is controlled by themovement and position of a cam slot II. In the form of the device shownln Figure 1 that slot is p formed directly in a worm gear I2 whichmeshes with the worm 9 and is carried on a shaft Iza. In the form of thedevice 4shown in Figure 2, the slot is formed in a rotary member I3which is attached to a shaft I4 of a servomotor X whose constructionwill be described in detail below. The second shaft I5 of the servomotorX carries at its exposed end a worm gear. I5 which meshes with the worm8.

In the form of the device shown in Figure 4, the `cam slot II is formeddirectly in a worm gear l1 which meshes with the worm I8 on the crankshaft III, the gear I1 being carried on a shaft Ila. In the form of thedevice shown in Figure 5 the cam slot I I is formed inA a worm gear` I9positioned on a shaft 20 and engaging a Worm 2| on a shaft 22 whichcarries a gear 23 meshing with a gear 2l on the crank shaft I0.

. From the above it will be seen that in each case the cam slot or cammember I'I is so connected by a variety of linkages with the shaft whichcontrols the drive of the cross feed screw 5 that lthis driveiscontrolled by the movementl and position of the cam slot II.

the `chuck and the work are driven from the vice shown in Figures 2 and4 no motor is shown. The belt 2l may be driven from any desired powersource. In the formof the invention'shown in I Figure 5 s,y separatemotor 8| is shown.

cutting tool l and the cutting operation is pro-` ceeding and a chip Ilappears as being cut from l the work piece by the cutting tool.

4Considering now in detail the form of the device shown in Figures 1 and2, the motor drives through the variable speed transmission 2l which asabove noted may be of any desired type and design. Two control levers u,I4 extend out from the transmission housing. These levers may be used tocontrol variations in output speed of the transmission. Certain types oftransmission will require one lever and others will require two.Therefore, although two are shown it is to be understood that vtheinvention is not limited to the use of two and one might be used or morethan two might be used.

From each control lever extends a link 3i. At the outer-end of each linkis al cam contacting member which ashere shown is preferably in the formof a roller carried by a pin 31 and each roller is received in a camslot Il in a movably or`slidably mounted cam plate 8l. It is to beunderstood, ofcourse, that if only a single lever u is used, there willbe but a single link Il, a single roller Il and a single cam slot Il.The cam plate is generally mounted for sliding movement and as hereshown is provided with a dovetail member 4I which fits into a.vcorrespondingly shaped guide 4I. 'I'hus the cam plate is mounted forcontrolled sliding movement.

In the form shown in Figure 1 the cam plate .Il carries a rack 42 whichengages a pinion Il 45 on a shaft M, the pinion being nxed on the shaft.

A loosely mounted pinion Il is also carried on the shaft and is providedwith a clutch portion or end Il. Keyed or splined on the shaft is aclutch .member Il, provided on its opposite faces with clutches Il andIl. A hand wheel Il is also rotatably mounted on the shaft u and isprovided with a clutch portion or face Il.

To control the clutch or coupling member I1 a handle member i2 isprovided. It is pivoted u on a support Il, has a handle M and a yoke Ilwhich engages the clutch I1. 'Ihe clutch or coupling l1 may itself bemoved so as to engage the loose pinion Il and thus secure the pinion tothe shaft M for rotation with it, ,or it may be moved in the oppositedirection to engage the hand wheel li andthus to secure it to the shaftI4 for lrotation with it. When the hand wheel is itself engaged, thedevice is in condition for manualsetting or adJustment and when the vupinion Il is engaged. the device is in condition for l automaticadjustment. The pinion 4l engages a movable rack l0 'which is mounted toslide in a support l1. At its outer end the rack is provided with anextension Il which carries a cam 7o contacting member, preferably aroller Il, which is carried on a pin Il. The roller lies within the camgroove Ii.

In the form of the device illustrated in Figure 2, the cam plate Il,instead of carrying a rack, .u carries an extension Il, which isperforated and pulley through the belt. In the form of the de- 'thechuck.

threaded to receive the threaded portion 62 of a shaft Il. The shaft issplined as at 8| and carries slidably mounted on the splines a pinion 65which engages a pinion 66 carried on a stub shaft l1 mounted finsuitable bearings. By means of bevel or other gears or connections B8the shaft O1 is connected to a hand adjusting shaft 68 which carries ahand adjusting wheel 10. A sup- 63 is progear Il which meshes with theworm s on the shaft l is a servomotor generally indicated in Figure 2 asX. The parts of theservomotor are shown in Figure 3 disassembled. Fixedto the casing of `the servomotor X is a disc 1I. A radial lug piston 'Itis carried on the inner face of the disc 1l. Fixed on the shaft i4 is asecond disc Il carrying a radial lug piston 1l. 'I'he disc 11.

is perforated by a hole 18 on one side of the lug 'Il and by a secondhole III on the opposite side of the lug 1I.

Fixed on the shaft Il-which carries at its outer end the worm vgear ilis a disc 8|. It is provided with a perforation l2, a second perforationIl, which on the upper face of the disc 80 joins 'and communicates withan angularly shaped escape slot Il. Il is a third hole or perforationthrough the disc Il which on the upper side of that disc Joins andcommunicates with a generally straight slot or groove 8l. v

Fixed to the housing of the servomotor X is a plate Il which has anannular outlet groove 88.-

and an annular inlet groove I9. A connection or conduit Il furnishes aconnection from the outlet groove Il and a connection or conduit sifurnishes a connection to the inlet groove 89.

In the form of the device shown in Figure 4, a variable speed frictiontransmission is shown as a means for driving the apparatus. As thereshown this'transmission is driven by a belt I2 which is driven from anysuitable power source. It drives a pulley Il and a shaft 04. The shaftis splined as at Il and is normally driven at constant speed. A smallfriction wheel I8 is mounted in suitable bearings 9"4 which form part ofthe frame from which an arm Il extends. The wheel Il is splined on theshaft l! and is so driven with it, irrespective of its longitudinalposition with respect to the shaft. The friction wheel st contacts theupper surface of the second friction wheel Il and thus drives it, andthrough it drives the shaft I". which is connected by any suitablegearing to drive the belt 21 and thus to drive the chuck 25. It is to beunderstood that any suit# able drive may be provided between the shaftINI and the chuck and the invention is not limited to any particularform or mechanism for transmitting power from the driven shaft i" to Atits outer end the arm 9| carries a pin iti upon which is mounted acontactroller |02. This roller lies within the cam groove |03 which isformed in a gear IM which is itself mounted on a shaft iMa. Meshing withthis gear is a pinion IUI carried on a shaft i which carries at itsopposite end a ratchet ill. On its outer end the shaft i carries anadjusting hand wheel IUI. A pawl i" is carried at the outer end of aswinging arm ill. A pawl connecting rod iii connects the arm Ii I withthe crank of the crank which carries a pin 13.

45 teeth m.

shaft I0. I |2is an adjustable shield carried at the outer end of an armIIB which is arranged to move, concentrically with the ratchet I 01 andcan be moved to cover or shield the teeth of the ratchet 5 |01 to limitthe number of teeth which can be engaged and consequently to limit theamount of travel of the ratchet at each reciprocation of the pawl.Joined to the arm I3 so as to form in effect an extension oi it is anarm ||4 which carries a pin lli upon which is rotatably mounted arollerl i6 `which lies within and engages the cam groove or slotv I I.'I'hus the position ofthe `roller within the cam groove controls theposition of the shield ||2 and so controls the movement of the ratchet|01 for each reciprocation.

The device 'ofFigure 5 is somewhat similar to that of Figure 4 anddiffers from it in the main bythe mechanism which controls the ratchetoperation. is a connectingrod mounted on the crank of the crank shaft Itand carrying `at its upper or free end a rack IIS. Suitable guides willbe provided for the rack to insure its movement along the proper path.They are omitted in the present drawings for the sake of clearness. Therack mesheswith a pinion IIC. which carries fixed to it a pawl arm |20which carries'at. its outer end'apawl |2I. ratchet |22. `The ratchet ismounted on a shaft |22 which carries at one end an adjusting hand wheell|24 and at the opposite end a contact arm |25 of a rheostat |28. Asshown the rheostat is connected by suitable wiring |21 with the motor 2|and the rheostat is moved or adjusted to vary the speed ofthat motor. Aplurality of contacts |22 are provided on the rheostat and the contactarm |25 in its movement contacts one .or another of the contact points|28 and thus suitably varies the speed of the motor. shield which may bepositioned to cover a number of the ratchet teeth and thus to limit themove-l ment of the ratchet wheel in response to recipro- J cation of thepawl |2|. This cover is carried on two arms Ill, one or bothof which maybe arcuate at its lower end and notched or shaped to provide These teethengage a rack |32 formed on the connecting member |32 which carries atits opposite end a pin |24 upon which is rotatably mounted a roller Il!which is positioned within and engages the cam slot or groove II in theworm gear Il. t.

In general with respect to the cam paths o r cam contours of the variouscams shown, these will be designed to suit not only the R. P. M. of thework in relation to the cutting radius of the cutting tool, but alsothey must be properly related to the speed ratio' of the variabletransmission and the selection of the particular type oi' variabletransmission will to somel degree govern the so cam path selected.However. the cam paths and O point at the wel is maintained t theinitial the relationship between the several parts which determine themcan' be established by formulae as follows: l

7 S equals any radius-of cut for which the revolutions per minute isrequired.

N equalsthe minimum revolutions per minute available.

u M equals resulting revolutions per minute for S.

The pawl may engage a |29 is an adjustable There is also the relationbased upon the cutl ting radii as follows:

No. 2. R

in whichv T equals minimum radius of cutting tool on the work.

P equals total ratio ot variable speed transmission frorn minimum tomaximum sneed.

There is'also the relation based upon cutting speed in feet per minute,which also bears the same ratio in corresponding revolutions per minute,which can be expressed as follows:

No. 3. Q

in which- Q equals maximum revolutions per minute available.

' Any cam path used as acontrol to vary the speed of the variable speedtransmission will agree with the above relations, irrespective of thetype of variable speed transmission selected.

The use and operation ofmy invention are as follows:

In the form of Figure 1 the cutting tool 4, either by hand ormechanically, is brought to position for beginning the cutting. shapingor finishing operation of the workpiece 32. This may be done with thetypical means provided on any standard lathe and during this initialsetting the coupling or clutch 41 is disengaged from the hand wheel l0and the pinion 4B and thus during this initial setting of the tool thespeed control cam plate 30 remains stationary. After the tool is set atthe initial point, the coupling or clutch 41 is moved to engage thehandwheel li the tool is setat the desired beginning point and i thecamplate l! is also setas desired. Now the coupling or clutch 41 is movedto engage the gear and any crosswise movement of the cutting toolautomatically moves the cam plate 2l according `to a predetermined speedand amount which is determined by the shape of the cam slot or groove inthe gear |2 and through the linkage shown and above described. The campath defined by the groove or slot. II is so designed as to vary theposition of the speed control cam plate Il so that the working speed atthe cutting determined feet per minute cutting speed, even though thetool `4 is constantly changing its cutting radius. Thus if the tool I ismoving in toward the center of the work piece 3 2 the cutting radius isbeing reduced and the speed of the chuck 2i is'being increased tocompensate for this reduction in radius. `To return the mechanism tobegin another -cycle when that becomes necessary, the lathe is reversedby means of the gearing normally used in lathes to return the tool andtool carrier and all other gears and cams will automatically follow inthe reverse movement.

It will be understood that in all movements of the cam plate Ilthecontact rollers 3l within the cam slots or grooves It are moved andthrough the members Il move the speed control levers Il to effect thedesired speed control of the variable speed transmission 29.

During vthe cutting operation the gearzl! is rotated. 'I'his rotation isaccomplished .by the rotation of the worm l which meshes with the gearl2. The worm I being fixed on the drive shaft a is rotated when it isdriven. This drive 'shaft is driven from any suitable power source,preferably at constant speed. It may be driven fromfthe motor 2l orotherwise. The cam groove` Ii is so shaped and proportioned with respectto thelimits of travel of the tool carrier,that when the tool is at itsextreme outside end of travel the contact roller il is in one end of thecam groove and when the tool carrier is at its extreme inner end oftravel the contact roller l! is in the opposite end of the groove. Thusthe cam groove Il makes one complete revolution or travel while the toolcarrier makes one complete cross travel with respectto the work piece. y

The device can be operated, of course, to drive in either direction andif the cutting tool begins its cutting at the center and moves outwardthe speed of rotation of the driving mechanism is reduced as the radiusof the cuttingv increases. Thus whichever way the tool "moves, the camplate Il is correspondingly moved, its movement being determined by theposition and movement of the cam groove Il, and a constant cutting-speed is maintained throughout.

An automatic disengagement mechanism may be provided so that at the endof the movement of the cutting tool in either direction the clutch orcoupling 41 is disengaged. A stop or stops can -be arranged to becontacted by the speed control cam 3l at the limit of its movement ineach direction to effect the throw-out lof the clutch 41. The operationof the form oi' the device shown in Figure 2v is substantially the sameas that 4shown in Figure 1 except that a servomotor is inserted in theassembly between the tool car- '45 rier l and the variable speed controlcam plate 8i. In the particular form shown, the servomotor ishydraulicallyvoperated. The power to rotate the member Il andthe cam Ilis furnished by the servomotor which may be driven by any high pressureliquid enteringthe motor through the conduit Il and leaving through the'conduit Il. The'angular rotation is controlled by a rotating valvevdisc ll upona shaft Il on the outer end of which' the w'orm gear It is56' mounted. -Movement of the worm gear 'it through the worm l, shaft I.gearing l and cross feed screw l effects movement of the tool carrier 3and tool 4. Any angular rotation of the disc Il and the worm wheel .willcause an 00 exact equivalent angular rotation of the shaft Il, themember I3 and the c amgroove. Il.

Movement of this cam groove is effective, through the roller 1I, the'shaft and the threaded portion of that shaft which is engaged in theind5 terioriy threaded extension'li ofthe speed control cam plate l), tocause-a corresponding variation in the speed of the drive lin the samemanner as movement of the plate 8l described in conf nection with Figure1 causes a variationin the 'l0 Aspeed eifective through the variablespeed unit 2l which is shown in Figure 1 but omitted fromy Figure 2.'Ihe tool carrier drive assembly above described is driven in the'samemanner as that described in connection with Figure 1. namely, 75 thedrive shaft` I is drivenfrom any suitable cam carrier I3 has been7omitted from the outer` endv of the shaft i4 'in Figure 3, to Vavoidcon' fusion. The disc Il of the'servomotor, since itV is carried by theshaft Ilwhich carries the work gear II, rotatesvwith the rotation of thecross feed screw i. The inlet hole 82 ofthe disc 8i, in its rotation,matches the hol Il in disc l1 and oil under pressure is permitted'topass into vthe'ispace between the iixedradial stoplt and the lug piston'Il on the disc 11. The disc 11 is thus rotated, due to oil pressure onthe side of the lug'pistonv 2l. The oil pressure is relieved on theopposite side bythe outlet 80. matching with the hole Il in disc Ilwhich discharged into the annular inlet conduit Il. 'I'he rotation ofplate Il successively uncoversy the hole l! and the outlet Il, thuscausing the disc 'l1 and its attached cam carrier I I to follow theexact an-i nular rotation of the driven disc BI. To return the disc fllto its starting point, the disc 8l is reversed and theslot or groove 88becomes the inlet to the hole Il and the slot 8l becomes the outlet fromthe hole 1l and the disc 'l'l thus follows the disc IlV in reversemovement in the same manner and for the same reason above described.

In general the operation of the form of the device shown in vFigure 2requires first a setting 'oi' the tool carrier 3 to the position whereit is desired to begin the cut or` finish on the work piece 32. This isaccomplished in the manner de scribed in connection with Figure 1. 'I'hemovement of the tool and tool carrier to the initial position must becarried out with the servomotor power applied ao that the relativemovement of the tool carrier and the cam li is maintained throughout,even during this adjustment period. The tool carrier ,itself is movedwith the typical or usual means' provided with any standard lathe. Withthe tool set in the desired initial position, the hand wheel Il isrotated and through the gearing shown rotates the gear OB vwhich isslidable on the splines oi'vthe shaft 8l. 'I'he shaft It is thus rotatedand through its threaded engagement with the extension 6| of the camplate $0 the latter is moved to move the variable speed control leversto the necessary position to effect the desired setting for the initialcutting speed which ia to be' given to the chuck.. This rotation of theshaft is possible because the mounting of the member 'I2 on vthe end ofthe shaft is such as to permit relative rotation of the With the initialsetting of the tool and of the camdisc 3l above described, any constantspeed power source. such as the motor shown in Figure 1. driving throughthe variable speed transmission device, is ready to deliver the properinitial rotating speed to the chuck 25 carrying speed is. of course,maintained constant even though the tool and the tool carrier lareconstantly changing their position, that is to say, their cuttingradius, and thus if the tool 4 is moving toward the center of the workpiece 32 the cutting radius is reduced and the R. P. M.

of the chuck 25 increases to compensate for this radial reduction.Should the parts b e moving in the opposite direction, the relationshipis maintained similarly so that the cutting speed remains constantduring movement oi' the tool irrespective of the direction of thatmovement.

To return the mechanism to itsoriginal posi tion to begin another cycle,the lathe is reversed by the gearing usually provided to move the toolcarrier and all parts, including the servomotor, will follow and willreturn to their original, ini` tial position and this will vbe repeatedwith successive cycles until a new initial setting oi the tool or of thecam plate 39 is desired and accomplished.

` As in the case of the form shown'in .Figure l, an automaticdisengaging means may be provided. It might comprise an end stop for thecontrol cam plate 39 to operate a stop valve or by-pass valve to cut oiIhydraulic power from the servomotor.

'I'he operation of the forms of the device shown in Figures 4 and 5 arein one respect at least similar because each of these formsembodied aratchet and pawl mechanism. Thus the variation in the speed of the chuckdrivein response to movements oi' the tool and the tool carrier is, inthese forms, not truly stepless as in the case of the earlier formsbecause the speed accomplished by the mechanisms of Figures 4 and 5 isin a sense a'step by step change. The steps are such that for manypurposes the speed change might almost be considered as being step- 40less but as a matter of accurate description it cannot be so describedand must be considered as being accomplished by a. series of steps.

In the form of the device shown in Figure 4, instead of the speedcontrol ca m plate 29 shown in Figures I and 2, a rotary cam groove |03is embodied in a carrying member |04. A shaft 94 is rotated from anysuitable power source and so rotates the friction wheel 96 which engagesa friction wheel 99, 'rotating it. The speed of rotation of the wheel esis dependent upon the distance of the smaller wheel 99 from the centerof rotation of the wheel 99 and this small wheel is moved in or out withrespect to the center of the wheel 99 Vby the movement of the cam discor groove |03.

0 Source.

As in the case of the preceding forms ofv the device, .the tool and toolcarrier are moved by a shaft which' is driven from any suitable power Inthe present form this shaft is the crank shaft I0. I n its rotation bymeans ci the worm .I0 it moves the worm gear I1 carrying the control"cam slot or groove A roller I|6 lies within and engages this groove andtraverses normally from end to end of the groove during one entire workstroke. The position of the roller I I6 controls the position of theratchet shield II2 and thus this shield is moved to vary the number ofratchet teeth which it covers and which it thus holds out of contactwith the pawl |09 which is reciprocated by movement oi' the crankthrough the connecting rod III. Thus the amount of forward movement ofthe ratchet is controlled by the position of the shield H2 and this inturn is controlled and is moved by the position and movement of the camslot or groove II.

When the device as shown in Figure 4 is to be used the cutting tool isbrought manually or otherwise' to the desired position for commencingthe cut. This ordinarily is accomplished by a rmechanism which forms apart of any standard lathe or similar tool. When the tool has beeninitially set at the desired point the hand wheel |08 is rotated in aclockwise direction, that is to say, in a direction opposite that inwhich the ratchet wheel will be driven in normal operation. This isnecessary so that the pawl |09 will not prevent rotation of the ratchet.Rotation oi the hand wheel |08 rotates the shaft |06 and through thepinion |05 which engages the gear |04', moves the speed control cam slotor groove |03 to a position which carries the friction driving wheel 96to a radius on the large driven friction wheel necessary to effect theselected initial cutting speed of the cutting tool, 4. Any constantspeed power source may be used to drive the shaft 94 and thus to drivethe friction wheels 98, 99 and the shaft |00, which latter is 'ment andthe degree of angular movement for each reciprocation is governed by theposition oi' the movable pawl shield ||2. The greater the number ofteeth covered by the pawl shield the less the angular movement of theratchet and correspondingly the less the rotation of cam slot |03, whichcontrols the variable speed.

The mechanism shown and just described thus accomplishes a variablespeed control of the chuck in which cam governs the movement andposition of the friction driving pinion or wheel 96 and the relativecontrol by means of which a constant cuttingspeed is accomplishedirrespective o! the position and movement of the tool is the same asthat accomplished by the form of the device shown in Figures 1 and 2,except that as above noted, the movement in the earlier forms isstepless while the movement in the form of Figure 4 is accomplished bysteps.

If it is desired to use the deviceof this gure both for cutting on areducing or an increasing radius, a reverse gear must be placed betweenthe cutting tool `and the worm drive, that is to say, between thecutting tool and the worm I8 and the worm gear I1.

An automatic end stop mechanism may be Y accomplished by providing meansto lift and to hold out of operativey movement the pawl |09, thisliftingto occur when the cam carrier gear I1 shall have moved to one orthe other limits of itsmovemen't.

The operation of the form of the device shown in Figure 5 is as abovenoted generally similar to that shown in Figure 4, themain difference`being that a rheostat is arranged instead of the second 4cam to governthe speed of the motor directly and thus to govern the speed of rotationof the chuck. Thus the rheostat is sub-f stituted for the cam |03 in thecam carrying gear |04. The introduction oi.' the racks IIB and |32provides means whereby the amplitude of the' pawl reciprocationmay beincreased and whereby a moreV sensitive operation is possible and thusvthe step from one speed change to the next is reduced and' this deviceinpractice acts more nearly like a stepl'ess/change device 6 than doesthe'formof- Figurel.'

The deviceof Figure 5 requires arreversegear to permit operationiin bothdirectionsr in the-'same manner and for thevv me reasons asf does thedevice of Figure l An automatic' disengagement'eiiective for example tohold ythe pawl [2l-fout of operative movemient may also' 'be' insertedin,the device of Figure 5 in the sam'e manrierasf' suggested for thedevice of-Figurei'. 'y

15 I claim:

1. In comblnatiori'fwith a lathe-or analogous machine, having aworkholder'and driving means respect to the work-holden andrfkiriving meanstherefor; automatic effective upon movement of` the tool hcld'erto-'varythe speed of the work holder drive to maintain'afconstant cutting speedat the tool, said means comprising a member driven in response tomovement of. the tool` holder drive; and' a` z crank linkage driven bysaid member'movement' toi-var;1 the speed of the work holder.l L .f

2. In combinatio' with a'lathoor analogous machine,y having, a work'holder and driving means therefor, aktpol' holderfrelutively movablewith respect to the, "work, 'hmgg and driving means therefor;l automaticmeansfeffective upon movement; of lthe tool holderto -vzary-the speed oftheworkfholder drive', tti-maintain. a constant "45 with 'respect totnewwora homer-'and driving means therefor; automatic means-[effectiveupon movement ofpthe .teal holder-te ieri' the speed of the work holderjd'iv and comprising a plurality of cams to. maintain a constant cutting50 speed at the tool.

4. In combination with a lathe or analogous machine, having a"wrkholderv and rotating means therefor, a tool holdervr radially movableywith respect to the -jwork holder, .and driving 55 means therefor;`automatic means 'eifective upon movement of Kthe tool holder to""varythespeed of the work holderjdrive-:to malntaina constant cutting speedat thetoolg. said means comprising a memberf'dri'ven in re'sgnse tomovement of the tool holder drive, ,andacrank linkage including' a linkanda levendriven by saidmember movement and' connected to said workholder drive,to varythespeedoffth work holder. 5. In combination withalath'e or analogous machine," having y a work holder and rotating meanstherefor,- a holderv radially movable with respect .to thejworkqholde'rand driving means` therefor; automatic meaiagmffective upon 70 movementof 'the tool holdelf-.tofciary the speed of the work holder 'drive tomaintain a constant cutting speed'at the tool; saidrgmeanscomprising acam member driven in response to movement of the tool holder drive, andalinltage including 75 a second cam driven by said c am member moveandrotating.

ment andconnected to said work holder drive to vary'thespeed ofthe workholder.

6.' InV combination with a lathe or analogous machine, having a workholding chuck. and a tool holder, together with means for moving thechuck andv for moving the tool holder with respect to the chuck and withrespect to a work piece on the chuck, means for maintaining a constantcutting speed, said `means comprising a cam member driven from the toolholder drive,

i and a speed control assembly, comprising linkage between said chuckmoving means and said member driven by said tool holder drive. saidlinkage. including a second cam, whereby movement of the latter effectsa corresponding movement. in the speed 'controlassembly and varies thespeed of the chuck drive in response to movement of the tool andmaintains a constant cutting speed.

7. In combination with a lathe or analogous machine,A having a workholder and driving means therefor, a. tool holder relatively movablewith respect to the work holder, and drivlng means therefor; automaticmeans eifective upon movement ofthe tool holder to vary the speed of theworkv holder drive to maintain a constant'cutting-speed at the tool,said means comprising a cam member driven in response to movement of thetooly holder drive, and a second cam member movably mounted, said secondcam member so connected to the driving means that its movement variesthe eiiective speed output of. said driving means, and a connectionbetween said first cam means and said second cam means whereby thelatterv is moved in correspondence to the former.

8.. In combination with a lathe or analogous machine, having af workholder and driving means therefor, a tool holder relatively movable withrespect to the -work holder, and driving means therefor; automatic meanseffective upon movement of the tool holder to vary the speed of the workholder drive to maintainl a constant cutting speed at the tool, saidmeans comprising a cam member driven in response to movement of the toolholder drive, and a second cam member movably mounted, said second cammember so connected to the driving means that its movement varies theeffective speed output of said driving means, and a connection betweensaid vfirst cam means and said second cam means whereby the latter is.moved in correspondence to the former, and a servomotor effective todrive said first mentioned cam means in response to movement of the workholder drive.

9 In combination with Aa lathe or analogous machine, having a workholder and driving means therefor, a tool holder relatively movable withrespect to the work holder and driving means therefor; automatic meanseffective upon movement of the tool holder to vary the speed of the workholder drive to maintain a constant cutting speed at the tool, saidmeans comprising a cam vmembe-r driven in response to movement of thetool holder drive, and a linkage driven by said cam member movement andconnected to said work holder drive to vary the speed of the workholder, and manual means for initially setting said automatic speedcontrol at a predetermined initial work driving speed.

10. In combination with a lathe or analogous machine, having a workholder and driving means therefor, 4a ltool holder relatively movablewith respect to the work holder, and driving means therefor; automaticmeans effective upon cutting speed at the tool, said means comprising acam member driven in response to movement of the tool holder drive, anda second cam member movably mounted, said second cam member so connectedto the driving means that its movement varies the effective speed outputof said driving means, and a connection between said first cam means andsaid second cam means whereby the latter is moved in correspondence tothe former, and manual means for initially setting said automatic speedcontrol at a predetermined initial Work driving speed.

11. In combination with a lathe or analogous machine, having a Workholder and driving means therefor, a tool holder relatively movable withrespect to the work holder; and driving means therefor; automatic meanseffective upon movement of thetool holder to vary the speed of the workholder'drive to maintain a constant cutting speed at the tool, saidmeans comprising a cam member driven in response to movement of the toolholder drive, and a second cam member movably mounted, said second cammember so connected to the driving means that its movement varies theeffective speed output of said driving means, and a connection betweensaid rst cam means and saidsecond cam means whereby the latter is movedin correspondence to the former, and a servomotor eiectlve to drive saidfirstl mentioned cam means in response to movement of the work holderdrive, and manual means for initially setting said automatic speedcontrol at a predetermined initial work.

driving speed.

12. In combination with a lathe or analogous machine, having a workholder and driving means therefor, a tool holder relatively movable withrespect to the work holder and driving means therefor;` automatic meanseffective upon movement of the tool holder to vary the speed of the workholder drive to maintain a constant cutting speed at the tool, saidmeans comprising a member driven in response to the movement of the toolholder drive,`and a linkage driven by said member movement to vary thespeed of the work holder, the means for driving said member from saidtool holder drive comprising a pawl and ratchet mechanism.

13. In combination with a lathe or analogous machine, having a workholder and driving means therefor, a tool holder relatively movable withrespect to the work holder, and driving means therefor; automatic meanseffective upon movement of the tool holder to vary the speed of the workholder dive to maintain a constant cutting speed at the tool, said meanscomprising a cam member driven in response to movement of the toolholder drive, and a linkage driven by said cam member movement andconnected to said work holder drive to vary the speed of the workholde'r, the means for driving said cam member from said tool holderdrivecomprising a pawl and ratchet mechanism.

14. In combination with a lathe or analogous machine, having a workholder and driving means therefor, a tool holder relatively movable withrespect to the work holder and driving means therefor;I automatic meanseffective upon movement of the tool holder to vary the speed of the workholder drive to maintain a constant cutting speed at the tool, saidmeans comprising a member driven in response to the movement of the toolholder drive, and a linkage driven by said member movement to vary thespeed of the work holder, the means for driving saidv member `from saidtool holder drive comprising a pawl and ratchet mechanism, and meansautomatically responsive to movement of said tool holder drive forlimiting the eiective stroke of said pavvl in accordance with movementof said tool holder.

15. In lcombination with a lathe or analogous machine, having a workholder and driving means therefor, a tool holder relatively movable withrespect to the work holder, and driving means therefor; automatic meanseffective upon movement of the tool holder to vary the speed cuttingspeed at the tool, said means comprising -a cam member driven inresponse to movement of the tool holder drive, and a linkage driven bysaid cam member movement and connected to said Work holder drive to varythe speed of the work holder, the means for driving said cam member fromsaid tool holder drive comprising a pawl and-ratchet mechanism, andmeans automatically responsive to movement of said tool holderV drivefor 4limiting the effective stroke of said pawl in accordance withmovement of said tool holder.

16. In combination with a lathe or analogous machine, having a Workholder and electric driving means therefor, a tool holder relativelymovable with respect to the Work holder and driving means therefor;automatic means eiective upon movement of the tool holder to vary thespeed of the work holder drive to maintain a constant cutting speed atthe tool, said means comprising a member driven in response to movementof said tool holder, and a linkage driven by said member movement tovary the speed of the work holder, said linkage including a ratchet anda rheostat effective upon said electric work holder driving means. i

ROBERT CRZELLITZER.

